1. Field of the Invention
This invention in general relates to the field of laser printing systems and, more specifically, to a modular optical print head which provides for the replacement of or interchange of laser component assemblies without requiring optical realignment.
2. Description of the Prior Art
The use of lasers, especially laser diodes, in optical print heads wherein pulses of optical radiation are utilized to produce an image or graphics, is well known. In a typical application, an image is produced by the scanning of the optical radiation across a suitable receptor medium. By way of example, the image may comprise alphanumeric characters or a graphical image formed either in gray scale or in color.
Laser diodes are advantageous for use in such applications because of their small size, high efficiency, and remarkable durability. Nevertheless, the use of laser diodes might be more widespread if not for their low power output (typically a few milliwatts), poor spatial quality, and relatively small number of output wavelengths. As a result, the use of laser diodes has been largely limited to applications which do not require a high intensity uniform source at one of the available output wavelengths.
As a consequence, a typical laser print head may utilize multiple laser diodes to provide an amount of radiative power suitable for achieving an acceptable printing speed. In U.S. Pat. No. 5,355,303 "Printing apparatus" issued to Ferla et al. and commonly assigned herewith, for example, there is disclosed a scanning print head comprising a plurality of radiation sources, or lasers.
It can be appreciated that the complexities associated with the alignment of a single-laser printing system are proportionately increased with a conventional multiple-laser printing system. Moreover, if one or more lasers fail while the printing system is in use, replacement will usually require realignment of each optical path, a complicated and time-consuming task.
While the art describes a variety of devices that utilize laser devices for printing, there remains a need for improvements that offer advantages and capabilities not found in presently available instruments, and it is a primary object of this invention to provide such improvements.
It is another object of the present invention to provide a laser print head device in which assembly and alignment are simplified.
It is another object of the invention to provide such a device and method in which individual laser units are replaceable or interchangeable without requiring optical realignment.
Other objects of the invention will be obvious, in part, and, in part, will become apparent when reading the detailed description to follow.